Enhanced capacitive deionization performance of activated carbon derived from coconut shell electrodes with low content carbon nanotubes–graphene synergistic hybrid additive

•Activated carbon derived from coconut shell electrodes for CDI desalination systems.•Synergistic effect of ultra- low content Carbon nanotubes–Graphene hybrid.•Excellent electrochemical performance of AC/Gr/CNTs (99/0.5/0.5 wt%).•Low cost, scalable approach to produce high-performance CDI electrodes. With increasing desalination demand worldwide, electrode materials for capacitive deionization (CDI) have attracted extensive attention recently. To compete with Reverse Osmosis, the performance of CDI electrode still needs to be further enhanced. In this work, graphene (Gr)/carbon nanotubes (CNTs) conducting hybrid was dispersed at as low as 1 wt% in coconut shell derived activated carbon (AC) to fabricate cost effective and high performance electrode for brackish water CDI desalination. The fabricated AC/Gr/CNTs electrodes show an excellent performance with the capacitance of 60 F/g (at 5 mV/s), the salt adsorption capacity of 9.58 mg/g and salt adsorption rate of 1.51 mg/g min at 1.0 V in 200 ppm NaCl solution. It should be highlighted that owing to the synergistic effect, the role of hybrid additive (1 wt%) was demonstrated to be more effective than that of single one, from a technical as well as from an economical viewpoint. To our best knowledge, this is the first study reporting the application of ultra-low content AC/CNTs hybrid in AC based CDI electrodes.